Date: Tue, 6 Apr 2004 12:10:40 +0400 From: "Artem Koutchine" <matrix@itlegion.ru> To: "Andy Farkas" <andyf@speednet.com.au>, "Xin LI" <delphij@frontfree.net> Cc: freebsd-current@freebsd.org Subject: Re: Qustion about being "Giant-locked" Message-ID: <004101c41bae$a9a419e0$0c00a8c0@artem> References: <C192C8912E798F4399668791C8965190674FD6@mx.hhp.local> <009401c41ba5$3b000f70$0c00a8c0@artem> <20040406071205.GA2819@frontfree.net> <20040406174155.S56300@hewey.af.speednet.com.au>
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>From: "Andy Farkas" <andyf@speednet.com.au> >Sent: Tuesday, April 06, 2004 11:56 AM > On Tue, 6 Apr 2004, Xin LI wrote: > > On Tue, Apr 06, 2004 at 11:03:13AM +0400, Artem Koutchine wrote: > > > While booting i see many drivers marked > > > as [Giant-locked]. > > > Is being Giant-locked good or bad what are the > > > implications? > > It's not good if you have a computer with multiple processors. > > I have a box with 4 ppro-200 cpus. It has 4 adaptec eisa scsi controllers, > each controlling 2 disks. All 8 disks are in the same vinum raid-5 volume. > I have a large (1.5gig) file on this volume. > > This is what happens when I run md5 on this file 4 times concurrently: > > > As you can see, only 8% of all cpus are being used to calculate the md5s. > At least 2 cpus are constantly idle. > > > ahc5: [GIANT-LOCKED] > atkbd0: [GIANT-LOCKED] I am trying to get your point and i really can't. I just don't see what your are trying to say. If you refer to 8% CPU usage then i see that it is only 8% because SCSI is the bottleneck. Disk just do not give data fast enough to load CPU high. Also, i don't think the do not give data fast enough only because of the Giant. I think it is mostly scsi and hdd speed problem in this case. Afterall md5 algorithm is not too havy on cpu anyway. Artem
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